The invention relates to an electronic element comprising:
a carrier having an electrically conductive mass plane;
a flipped chip die mounted on said carrier, said flipped chip die having a backside opposite to a front side directed towards the carrier; and
an electromagnetic interference shield electrically connected to the mass plane of the carrier.
Electromagnetic interference (EMI) problems are well known. EMI is a particular problem in cellular phones in which an antenna emits radio frequencies (RF) which could affect the other circuitry operating in the phone.
For solving this problem, it has been proposed to use EMI shielding.
U.S. Pat. No. 6,092,281, the content of which is incorporated in the present specification by reference, teaches such an EMI shielding.
In the shielding of U.S. Pat. No. 6,092,281, the carrier is provided with electrically conductive dams forming a chamber or pocket, the bottom of which is a portion of the carrier. In said chamber, the flipped chip is placed. The chamber or pocket is closed with an electrically conductive cover distant from the flipped chip. The free space between the flip chip and the dams and cover is filled with an electrically insulating encapsulating material.
The production of such shielding is expensive, as it requires separate shielding cover, formation of dams, soldering operation, filling operation with insulating encapsulating material, etc.
The invention seeks to provide an electronic element, which provides shielding without requiring the use of dams or a cover to be soldered to dams.
In accordance with the invention, this object is accomplished in an element of the type disclosed in the first paragraph of the present specification, in that the electromagnetic interference shield comprises an electrically conductive means electrically connecting an electrically conductive layer on the backside of the flipped chip die, preferably covering the whole backside of the flipped chip die, to the mass plane of the carrier.
Advantageously, the conductive means electrically connects the conductive layer on the backside of the flipped chip die to the mass plane of the carrier, so as to make a faraday cage around the die.
Preferably, the electrically conductive means electrically connecting the conductive layer on the backside of the flipped chip die to the mass plane of the carrier comprises conductive glue and/or a conductive tape.
According to another embodiment, the electrically conductive connection means, connecting the conductive layer on the backside of the flipped chip die to the mass plane of the carrier, comprises a conductive connection through the die, connecting the conductive layer to bond pads on the front side of the die that is connected to the carrier.
The invention further relates to an apparatus comprising an electronic circuit comprising at least an element of the invention.
Preferably, it comprises at least an antenna for emitting a radio frequency. The apparatus of the invention is for example an apparatus for GSM and DECT applications.
Details and characteristics of the invention will appear from the following description in which reference is made to the attached drawings, wherein:
FIG. 1 is a partial perspective view of an electronic element of the invention, partially cut away and with a covering mold component in interrupted line;
FIGS. 2a and 2b are cross-sections of the electronic element of FIG. 1;
FIGS. 3a and 3b are cross-sections similar to FIGS. 2a and 2b, but pertaining to other embodiments of the invention.